Construction on the wall Donald Trump made central to his presidential campaign—one that he repeatedly promised would run the length of the U.S.-Mexico border, geological and fiscal impossibilities be damned—has yet to begin, which might be a good thing, since Trump apparently has some new design notes for how he’d like the wall to be built.

Asked by reporters aboard Air Force One on Wednesday night about the wall, the president offered several perplexing new details about his plans and insisted that he was “not joking” about adding solar panels, a proposal he earnestly suggested would help cover the project’s estimated $21.6 billion cost. “There is a chance that we can do a solar wall,” Trump said. “We have major companies looking at that. Look, there’s no better place for solar than the Mexico border—the southern border. And there is a very good chance we can do a solar wall, which would actually look good. But there is a very good chance we could do a solar wall.”

Trump went on to say that the wall needs one thing: transparency. “You have to be able to see through it,” he explained. “In other words, if you can’t see through that wall—so it could be a steel wall with openings, but you have to have openings because you have to see what’s on the other side of the wall.”

The wall needs to be see-through, the president continued, because drug dealers may otherwise throw large bags of drugs over the wall to the other side, and hit innocent passers-by. “As horrible as it sounds, when they throw the large sacks of drugs over, and if you have people on the other side of the wall, you don’t see them—they hit you on the head with 60 pounds of stuff? It’s over,” he added. “As crazy as that sounds, you need transparency through that wall. But we have some incredible designs.”

Trump promised on the campaign trail that he would find a way to make Mexico pay for the wall. A new spending bill released by House Republicans this week proposes $1.6 billion to begin building the border wall. Mexico has no plans to pay for any wall along the U.S.-Mexico border, transparent or otherwise.